/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package com.aliyun.oss.utils;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.security.DigestInputStream;
import java.security.MessageDigest;

public class StreamUtils {
    
    public static String readContent(InputStream contentStream, String charset)
            throws UnsupportedEncodingException{

        InputStreamReader reader =
                new InputStreamReader(contentStream, charset);
        BufferedReader br = new BufferedReader(reader);
        StringBuilder sb = new StringBuilder();
        String line = null;
        try {
            while((line = br.readLine()) != null){
                sb.append(line);
            }
            return sb.toString();
        } catch (IOException e) {
            return null;
        }
        finally{
            try {
                br.close();
                reader.close();
            } catch (IOException e) {
            }
        }
    }

    public static String calculateMD5(InputStream in) throws Exception {

        DigestInputStream ds = new DigestInputStream(in, MessageDigest.getInstance("MD5"));
        while (ds.read() != -1) {
        }

        byte[] md5bytes = ds.getMessageDigest().digest();

        StringBuilder sb = new StringBuilder();
        for (byte md5byte : md5bytes) {
            String hexBiChars = String.format("%02x", md5byte);
            sb.append(hexBiChars);
        }

        return sb.toString();
    }
}
